The invention relates to a cyclone separator comprising first and second cyclone arrangements connected in series.
Cyclone separators having a known type of construction are used in many devices for removing impurities from a gas stream. Such impurities can be dust particles, droplets of a liquid or the like. In particular, it is well known to arrange a cyclone separator in a crankcase ventilation system of an internal combustion engine. So-called blow-by gases are conveyed via the crankcase ventilation system to the air intake tract of the internal combustion engine. It is desirable to remove oil droplets entrained in the gas stream as completely as possible.
To separate entrained contaminants, the gas stream is directed approximately tangentially into a cyclone with an approximately round cross section. This causes a rapidly moving eddy to form. The centrifugal forces acting on the entrained contaminants cause these impurities to be deposited against the cyclone wall. Contaminants separated in this way can be removed from the lower area of the cyclone, e.g., with the aid of gravity. The resulting cleaned gas stream is discharged from the cyclone in the area near the cyclone axis.
In many applications, particularly in a crankcase ventilation system, the requirements to be met with respect to the cleaning efficiency of the cyclone separator are high. To increase their efficiency, it is known to connect cyclone separators in series in the manner of a cascade, such that the gas is pre-cleaned in an initial cyclone arrangement, which is arranged first in relation to the flow direction through the separator, and further cleaned in one or more downstream cyclones. Such multi-stage cyclone separators can be designed to function within a specific operating range as regards their cleaning action and flow resistance indicated by the pressure loss as the gas flows through them. However, it is difficult to design a cyclone separator suitable for cleaning gas streams across a broad range of volume flow rates. If the cyclone separator is adapted to the maximum volume flow that occurs, the cleaning action may be insufficient at lower volume flows. On the other hand, if the cyclone separator is adapted to, for example, an average volume flow, then the flow resistance may become excessively high at a maximum volume flow.